The present invention relates to an antifriction bearing which resists heat, particularly heat applied at an axial end of the bearing. The bearing has particular application for exhaust gas turbochargers.
Exhaust gas turbochargers operate at a high speed rotation. In addition, they develop high temperatures. In particular, high temperature is applied at one axial end of the bearing. This combination of operating conditions makes extreme demands on the precision and heat resistance of the mounting of the bearing.
Plain bearings were used in order to support the shafts of the turbocharger. A change has recently been attempted to use anti-friction bearings. See European Unexamined Application 87 834 and German Unexamined Application OS 36 17 402. In such bearing units, standard anti-friction bearings are arranged on a shaft axially spaced from each other. The bearings are axially pre-tensioned by springs to obtain the desired precision and are cooled by various expensive cooling means. These create complicated mountings and their operating action is not predictably optimal.
An anti-friction bearing unit in which the invention is used comprises two anti-friction bearings which are axially spaced apart from each other along a shaft. Particularly in a turbo charger, the two bearings are arranged so that high temperature occurs on one axial side of the shaft covering one of the two bearing rows.